My experience was unorthodox, but convinces me this stuff is great. I had part of a roll given to me for free. Last summer was my first in this *old* mobile home, which is loaded with windows. There is not one tree here for shade, but since I'm on a hill there's always a breeze. On a whim, I put this stuff in some of the windows. Looked pretty stupid, but it kept the temps much, much cooler than if I'd let the sun shine in all those windows. It worked like heavy drapes, only better. I'm going to buy a roll this summer for the rest of the windows and inside the roof of the new goat shed.